Radiocircuit



Aug. 21, 192s. 1,681,274

R. c. BAIRD ET AL RADIOCIRCUIT Filed July ll, 1927 n I p hm si Nunn Attorney.

(itl

L2 which is interposed in the plate circuit of the audicn A1, the inductive coupling being effected through the series wound coils LJ and L, connected by the conductor (10'). 'l`he coils L2 and Lg are wound on the same tubing but separated from each other, whercas the coil Ll is wound on a smaller cylinder which is inserted within the larger.

The inductance L.; is tuned by the variable condenser C2 which is placed in parallel to said coil. The coil L... and variable condenser C: are connected to the plate through the conductor (l1). The coil LI is connected to the grid through the conductor (12), grid leali (13), fixed condenser C4 and conductor (it).

The grid leali (13) and condenser (l1 are in parallel with each other and placed between the grid (i: and the intersection ot the conductor (12) and the conductor (15) which is connected to one side of the variable condenser Cit, the other side thereof being connected to the plate terminal pl of the primary coil ot the first audio transformer T, through the conductor (11S) and a portion of conductor (19).

Returning to the tuned inductance L., it will be noted that one terminal thereof is joined to the positive side of the 13" bat'- tery (17) through the conductor (1H) thus permitting the same positive charge of this li battery to be impressed on both the plate P2 and grid G2 of the reetitying audion when there is no additional positive or negatire incoming signal impulse.

The negative side of the B battery (17) is connected through Conductor (17') to the (21 terminal of the primary ofi the first audio transforn'ier T` which is bridged by the fixed condenser Cn. The plate terminal p1 of the .first audio transformer is connected through the conductor (19) to the filament terminal f] of the same, which in turn is connected to the positive side B of the filament circuit through the conductor (2t) The audions A3 and A, which are utilized as amplifiers are connected in the ordinary cascade manner7 that is the grids Gl., and G4 of :italiens A;i and Ai are connected to the grid terminals g1 and if/2 of the secondary coils of the first and second audio transformers T, and T2 the opposite terminals fl and f2 being connected through the conductors (21), (Q2) and (Q0) to the negative side of the filament circuit.

The plates 1) and 1) of these audions are respectively connected, through the prin'iary of the second audio transformer TL and through the phone or speaker jack ((3) to the positive side otl the B battery (10).

For a better understanding of the. operation of the detector, reference may be had to the diagram shown in Fig. 2.

The radio frequency output of the coil L2 is nductirely impressed upon the coils L,

and L.; whereupon, depending on the phase characteristic of the signal the path of thc incoming current will be as follows: through the conductor (11) to the plate l. and

through the conductor (15), condenser (et,

and conductors (113) and (17') to the pri mary of thc first audio transformer "Il, thence through conductor (15)) and bus bar VU to the filament lf2, thereby establishing a li i battery current through the conduetors (15)), (ll), and plate l2 and bacl: to the negative side of the .li l battery through the filalnent lf2.l conductor (19), the primary ot the first audio transformer and conductor (17') When the phase characteristic of the signal is in the opposite direction the path of the incoming current will be through the conductor (12). grid leak (13), cmnlenscr (1 conductor (Lf) and to grid tb., and through conductor (1S), the B battery (17), conductor (17')7 primary of the first audio transformer 'l` conductor (19), bus bar l and to the filament- Fg, thereby estabfishing the l battery current through the condlu'tor (18), coils L3 and 11 conductor (12). grid leali (13), conductor (14) and to the grid (2 and back to the negative side of the l battery through the filament lf2, busbar B, the conductor (1U), the primary of the, first audio transformer and conductor (17').

1t is readily seen from the above operation that the detector functions alternately in rectifying the positive and negative incoming impulses.

ln conclusion it will be manifest this system enables utilization of a portion of the radio frequency impulse which is ordinarily discarded and enables this double rectification to be performed through the medium of' the conventional audion tubes. Moreover, by including the primary coil of the audio transformer in plate. and grid circuit aml'ilificatirm is obtained 'for both the positire and negative phase elulracteristics of the input oscillation.

Having described our invention, what we claim as new and wish to secure by Letters Patent is:

1. ln a radio receiving system an input circuit. a detector including plate. grid and filament7 means for impressing the input oscillations across both grid and filament and plate filament. such means including a trio of inductively associated coils. two of the latter being series connected and means for impressing a` constant voltage of corresponding value on both plate and grid.

2. ln a radio receiving system an input circuit. a detector including plate, grid and filament, means for impressing the oscillations of the input across grid and filament and plate and filament, means for impresing a constant Voltage of equal value on lli lItfJ both plate and grid, an amplifying circuit including an audio transformer the primary of said transformer being included in both the plate and grid circuit of the detector.

3. In aV radio receiving system an input circuit, a detector including plate, grid and filament, means for impressing the input oscillations across grid and filament, plate and filament, such means including a. plurality of inductively coupled coils, means for impressing a constant voltage equally on both plate and grid, an amplifying cirm cuit, a transformer therefor, the primary of said transformer being included in the plate and grid circuits of the detector.

4. In a radio receiving system an input circuit, a detector including plate, grid and lament,` means for impressing the input oscillations across grid and filament, plate and filament, such means including a trio of coils inductively associated, one of said coils being in the input circuit, the remaining coils being series connected and arranged in the plate and grid circuits, means for impressing a constant voltage equally on both plate and grid, an amplifying ciry cuit, a transformer therefor, tbe primary of the transformer being in both plate and grid circuit.

RAYMOND C. BAIRD. EUGENE E. SNELL. 

